Ir] Potato Disease and Allied Diseases 31 
rot from spreading in the clamps. Ground lime at the 
rate of 1 cwt. to every ton of potatoes, or flowers of 
sulphur at the rate of 2 lbs. to every ton of potatoes, 
have proved very successful in preventing the spread 
of winter rot. 
<== oe 
~~ Ca 
Fig. 10. Tomato seedlings, one healthy and the other killed by 
the damping off fungus Pythium de Baryanum. 
Damping Off (Pythium de Baryanum). 
In seed beds a number of seedlings are often found 
lying prone on the ground, the stem of the plant being 
rotten just at the ground level (see Fig. 10). This 
state of affairs is known as damping off. There are 
several fungi which cause young plants to damp off in 
this way, one of the commonest being Pythium de 
